Income Taxes - Components of Income Tax Expense (Benefit) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ 0	$ (21.2)	$ 3.2
Current State and Local Tax Expense (Benefit)	3.5	(2.3)	6.9
Current Income Tax Expense (Benefit)	3.5	(23.5)	10.1
Deferred Federal Income Tax Expense (Benefit)	(1.5)	14.9	(9.4)
Deferred State and Local Income Tax Expense (Benefit)	0.3	(3.1)	(1.0)
Deferred Income Tax Expense (Benefit)	(1.2)	11.8	(10.4)
Federal Income Tax Expense (Benefit), Continuing Operations	(1.5)	(6.3)	(6.2)
State and Local Income Tax Expense (Benefit), Continuing Operations	3.8	(5.4)	5.9
Income Tax Expense (Benefit), Continuing Operations	$ 2.3	$ (11.7)	$ (0.3)